Cranelift: Add .wat to assembly test support and generate Wasm load/store tests for all ISAs (#5439)

* cranelift-filetest: Add the ability to test `.wat` to assembly

* Make the load/store test case generator script use `.wat` tests

And generate tests that exercise both Wasm-to-CLIF lowering and Wasm all the way
to assembly.

* Remove old versions of generated load/store tests

* Add new generated load/store tests

* Fix filename reference in script

cranelift/filetests/src/test_wasm/config.rs

@@ -15,6 +15,9 @@ pub struct TestConfig {
     #[serde(default)]
     pub target: String,
 
+    #[serde(default)]
+    pub compile: bool,
+
     #[serde(default)]
     pub settings: Vec<String>,